year = 2004
month = 4
if month == 1 or month == 3 or month == 5 or month == 7 or month == 8 or month == 10 or month == 12:
    print("31天")
else:
    if month == 2
        if yaer % 100 == 0:
            if year % 400 == 0:
                print("29天")
            else:
                print("28")
        else:
            if year % 4 == 0:
                print("29")
            else:
                print("28")
    else:
        print("30天")